The present invention relates to a semiconductor structure and a method of fabricating the same. More particularly, and in one embodiment of the invention, a programmable anti-fuse structure containing a diamond like carbon (DLC) anti-fuse material with different programming efficiency is provided.
The manufacture of integrated circuits (ICs) typically includes the formation of metallization layers which are patterned to provide interconnection between devices. Some IC interconnections are programmable, either with fuses or anti-fuses. Non-programmed fuses provide a low resistance link between or within metallization layers which can be programmed by being blown. That is, the fuse can be caused to be non-conductive by applying a sufficiently high current across it to blow.
Anti-fuses operate in the opposite fashion, i.e., the non-programmed structure used to form the anti-fuse has an intrinsically high resistance, and the programmed structure has a relatively low resistance. By applying a programmable current, the electrical resistance through the anti-fuse material is greatly reduced providing a conductive link between or within metallization levels. Programming of typical anti-fuse structures can be accomplished by providing a voltage of 4-10 volts between the metal layers. Before programming, the anti-fuse structure typically has a resistance of above 1 giga-ohm for a 1 μm diameter via. A programmed anti-fuse forms a conductive path between the metal layers having a resistance of about 20-100 ohms.
Anti-fuse structures allow for much higher programmable interconnection densities than standard fuse structures as well as smaller current and power for the non-programmed elements. Anti-fuse structures have been used in the semiconductor industry for memory related applications, such as, for example, field programmable gate arrays and programmable read-only memories. As indicated above, anti-fuse structures include a material which initially has a high resistance but can be converted into a lower resistance by performing a certain application. For example, an unprogrammed anti-fuse type gate array can be programmed by causing a selected anti-fuse type to become conductive.
With shrinkage of feature dimension, it's required to decrease programming voltage in order to enhance programming efficiency and meet technology compatibility.
Decreasing the dielectric oxide thickness may be a potential approach to meet the requirement of decreasing the programming voltage. However, decreasing the dielectric oxide thickness not only causes uniformity control problems, but also it is a challenge to have a contact sitting and stopping on the thin dielectric oxide film.